Is there a way to do Render Time Booleans in Houdini and Mantra?

I have some pretty detailed and numerous CAD parts that I will eventually have to show the interior of the assembly to display the functionality.

I'm having a lot more success using Clips instead of Cookies to cut the models and getting a cap. More success than 3DS Max as well as I would have to manually do this for every single peice instead of the procedural way I have going in Houdini.

But I'm only manually doing this because Vrays method of Render Booleans (VrayDistanceTex and duplicate geo) takes extremely long to render. From 45 minutes at 1080p to 6 hours a frame for my scene. This seems to be a known issue from the ChaosGroup forums but pushed aside as Render Booleans seem to not be used often. This lets me animate the outside-to-in transition though, instead of doing a fade away from full model to cut. Just Trying to be fancy.

Using my Clip Method I can't do the animated transition. I'm probably missing a step that I'll have to investigate, but it's still an aside.

Modo looks to have some nice Render Booleans but I'm curious if there's a way to do this with Houdini and Mantra. Just now exploring the shader route but it's not something I'm too fluent in yet.

Thanks.

PS: Wish these forums would fix the stuck drop shadow on the #mainContainer#shadowRight/Left.shadow_image{ display: none }

Ok here is a quick try. This is nice as any kind of geometry works: here we have a primitive sphere cutting a nurbs torus and polygon boxes.

This is a bit of an old-school approach, I count the intersections that happen along the viewing ray inside the cutting sphere - if there is an odd number of them we are inside of your object and we shade the backside of our cutting sphere, if there is an even number of them, we shoot the ray from the far side of the sphere and it continues as if nothing happened. The surfaces need to closed (manifold, I guess) for this to work.

There are some precision issues if you look closely, you will need to play with the raytrace biases depending on your scene size. Also, you would need to incorporate the shader for your cut surfaces into this one. I wouldn't vouch for this approach to be production proof, but it just might cut it

eetu! That's awesome, thanks so much for your time! I just quickly threw in one of my objects and modified the cutter and it works straight away.

Your explanation and the hip file are a great help to learn. It doesn't seem to work when Mantra is set to PBR though (only Raytrace). I'll have to find some time to get that to work and perhaps set it up as a tool to selectively have objects to be cut, and cutters and shader integration. As some of the work I do this would be a huge boon.

Thanks again!

awesome & incredible…
but have way to visualize in view port too?

Wow this is an awesome thread. Brilliant. Never thought about this

Nice trick; might be fun take on those FX How-To videos. We're always looking for ways to spice those up a bit. (Don't forget to add this to eetu's lab over on oddy)

http://forums.odforce.net/topic/8471-eetus-lab [forums.odforce.net]